| The fat of Ningxia Tan sheep was used as the research object in this paper.The difference metabolites were detected of fat in the chilled storage period of 0,4,8 and 12 days by GC-MS and LC-MS techniques based on the Omics Bean cloud platform.It aimed that found precursors and intermediates of flavor substances and the relevant metabolism pathway.Discussing the process of precursors and intermediates of flavor substances change after slauter based on substances exchange asbact by Metabonomics.1.The differential metabolites of the cold storage of chilled Tan Sheep fat for 4d vs.0d,8d vs.4d,12d vs.8d was identified 64,65,27 species and 99,75,70 species by GC-MS and LC-MS,respectively.It indicated that the types of differential metabolites decreased with the prolongation of storage time.After storage for 8 days,the content of the bitter taste and umami flavors of hypoxanthine,alanine and threonine increased significantly,while the precursors of various flavor substances such as oleic acid,palmitic acid and stearin produced by fat.The content of acid and the like is significantly decreased.The phenomenon that flavor precursors and intermediates change over time during storage will provide a theoretical basis for how to meticulously study the storage conditions of cold meat.2.The differential metabolic pathways were identified 104,108,69 and 18,31,15 by GC-MS and LC-MS,respectively.It indicated that the quantity and type of metabolic pathways also increased first and then decreased with the prolongation of storage time,also.At 0 to 4 days,the galactose metabolic pathway was significantly different(P=2.76×10-4<0.05),while the oxidative phosphorylation pathway did not differ,but the metabolic pathways related to the flavor precursors oleic acid,palmitic acid,and stearic acid.There was no difference during this period;within 4 to 8 days,the fatty acid biosynthesis pathway(P=6.65×10-3<0.05)and GnRH signaling pathway were significantly different(P=4.67×10-2<0.05),biosynthesis of unsaturated fatty acids The pathway was also significantly different(P=3.24×10-1>0.05)and significantly different(P=5.87×10-5).After 8 days,there was no difference in fatty acid biosynthesis pathway and GnRH signaling pathway,and the biosynthesis pathway of unsaturated fatty acids was not different.Significant(P=1.57×10-1>0.05).3.The precursor substance of synthetic palmitic acid,3-hydroxybutyric acid and 3-oxohexadecanoic acid,was found in the differential metabolite.The results showed that there was no difference in fatty acid synthesis pathway at the initial stage of storage,but the relative content of short carbon chain compounds related to palmitic acid changed,the relative content of 3-hydroxybutyric acid and 3-oxohexadecanoic acid varied within 0 to 4 days.Significantly;after a period of time,the palmitic acid decomposition and the fatty acid ? oxidation pathway were opened in the pathway,and the relative content of palmitic acid decreased significantly at 4 to 8 days.The fatty acid biosynthesis pathway is initiated by the formation short chain compounds such as 3-hydroxybutyric acid and 3-oxohexadecanoic acid by a variety of oxoylases,fatty acid synthase enzymes and acetyl-CoA at 0 to 4 0C for 0 to 4 days.Malonyl-CoA is present as an important two-carbon unit provider in fatty acid synthesis.The study of metabolic pathways and their changes can be used as a new perspective to reveal the progressive failure of post-mortem tissues.At the same time,as a bridge connecting proteomics and genomics,the metabolic pathway transformation process is also the metabolic process of the body and tissues after slaughter.The process of transferring each substance,energy and genetic information in the time period.Studying the transformation of metabolic pathways can provide basic theoretical guidance for the cold storage and transportation technology of Tan sheep products,and provide theoretical support for the improvement of the quality of cold fresh beach products and the extension of shelf life. |
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